The invention relates to a buckle of a binding and tightening device of a sport boot on a sliding board, particularly suited to the snowboarding bindings, allowing two levels of binding. It also relates to an application of such a buckle in a device for the tightening and closure of rigid boots of the ski boot type. It finally relates as such to several devices incorporating the buckle of the invention such as a device for attaching a boot to a sliding board and a sliding board fitted with such a binding device and a sport boot with such a device for its closure and tightening.